Rack arrangement using movable racks has been known. In Japanese Patent Publication No. 2-19044, for example, there is proposed a movable rack arrangement wherein a plurality of longitudinally extending movable racks are back and forth movably arranged within a space defined by a support structure and the like so that a working space may be provided in front of the facade of each of the movable racks. On the support structure side and above the movable racks are arranged in parallel opposed relation a pair of rails extending along the length of the movable racks, with arms adapted to be movably guided by the rails. There are also provided forks which are movably guided by the arms and upwardly and downwardly movable.
According to this known arrangement, by moving plural movable racks it is possible to provide a working space in front of the facade of a target movable rack. Each fork is movable within the working space through the movement of the associated arm, and transfer of a load to and from a target location is possible through the operation of the fork.
In such prior art arrangement, however, the rails must be rigidly fixed to the support structure through support members, such as brackets; and naturally the support members are large-sized, particularly in their vertical aspect. This makes it necessary to provide considerable space above the movable racks. In other words, the provision of the support structure for the rails results in decreased storage efficiency of the movable racks. Additionally, the support structure must be large-sized in order to sustain the arm-side load.